The statements in this section merely provide background information related to the present disclosure and may or may not constitute prior art.
In many modern motor vehicle transmissions, the essentially completely mechanical automatic transmission having planetary gear assemblies and hydraulically operated clutches and brakes has been superseded by transmissions having electronic controls and a plurality of sensors and solenoids. The sensors provide data relating to, for example, shaft speeds and actuator positions and the solenoids engage and disengage synchronizers and gears. Current dual clutch transmissions (DCT's) are excellent examples of this technology.
Size and packaging constraints of such dual clutch transmissions often mean that relatively powerful solenoids are located proximate speed and position sensors. This may result in one or more speed or position sensors being exposed to the magnetic fields of one or more of the solenoids. Since the solenoids will be repeatedly energized and de-energized during shift activity, the magnetic field disturbances they create can adversely impact the output signals of the speed and position sensors.
The obvious solution to this problem is to re-locate either the solenoids or the sensors. Unfortunately, re-locating the solenoids in a final or near final transmission design is akin to the tail wagging the dog: the power flow through the transmission and the shaft, synchronizer and gear arrangements take precedence over the locations of the solenoids. Re-locating the sensors is generally equally unfeasible because there are often only very narrowly defined locations where a particular motion or rotation may either be conveniently sensed or sensed at all.
Thus, it is apparent that new solutions to the problem of electromagnetic interference of sensors in transmissions are necessary and the present invention is so directed.